1. Field of the Invention
The present invention relates to an image reading apparatus for reading an image from a transmissible original or reflective original and converting it into an electrical image signal.
2. Related Art Statement
In the past, for example, Japanese Unexamined Patent Publication No. 7-23180 has proposed an apparatus as an image reading apparatus for reading a non-transmissible original that is a reflective original or a transmissible original and converting it into electrical image information. An image signal output from the image reading apparatus is converted into digital data, transmitted to, for example, a personal computer or the like, and then utilized.
FIG. 14 is a sectional view of an image reading apparatus disclosed in the Japanese Unexamined Patent Publication No. 7-23180, showing a state in which a reflective original is read. FIG. 15 is a sectional view of part of the image reading apparatus in a state in which an image on a transmissible original is read. The image reading apparatus comprises a transmissible original station 102 which includes a light source unit 103 and on which a transmissible original 1 to be placed on the top of a main unit 101 is stationed, a reflective original station 104 including an original station glass plate 105 on which a reflective original 2 is stationed, a sub-scan drive motor 106 incorporated in the main unit 101, a timing belt 107 to be driven to rotate by means of the drive motor 106, a guide shaft 108 lying parallel to the timing belt 107, a reader 109 engaged with the timing belt 107 and moved along the guide shaft, and a transmissible original image formation optical system 110 located below the transmissible original station 102 and composed of an image formation lens and mirror.
The reader 109 includes a light source unit 111, an imaging optical system 112 composed of a mirror and image formation lens, and a line sensor 113 for converting a linear image extending in a main-scan direction into an electrical image signal.
As mentioned above, when the conventional image reading apparatus having the foregoing components reads a reflective original, the reflective original 2 is stationed on the glass plate 105 of the original station. The original 2 is held with the flatness thereof maintained by a cover. The reader 109 is driven in a direction X2, that is a sub-scan direction, by means of the drive motor 106, whereby an image is read from the reflective original 2.
For reading an image from a transmissible original, the reader 109 is, as shown in FIG. 15, moved to a position near the transmissible original station 102, and thus set to a state in which light transmitted by an original is routed to the line sensor 113 by the transmissible original illumination unit 103, imaging, optical system 110, and reflector. In the set state, the transmissible original 1 is driven in a direction X1 that is a sub-scan direction by means of a transmissible original driving means (not shown) included separately. Thus, the image on the transmissible original 1 is read.
However, in the image reading apparatus disclosed in the Japanese Unexamined Patent Publication No. 7-23180, the reflective original station 104 and transmissible original station 102 must be located on the main unit 101, and the light source units 111 and 103 must be located at different positions. This leads to the large main unit. Furthermore, as a sub-scan driving mechanism important to input a high-definition image, mechanisms dedicated to a reflective original and transmissible original respectively must be included. This increases cost. Moreover, depending on whether an original is the transmissible original or reflective original, the setting of the image reading apparatus must be modified by a user, that is, the position of the reader 109 must be changed by a user. Thus, poses an inconvenience.